FATAL ERROR on png transparency check.

Whenever your plugin starts processing a png image and for some reason that image has errors it will fatally crash instead of producing a warning or ignoring the check.

Here’s the error produced by your plugin:

PHP Fatal error:  Uncaught TypeError: imagecolortransparent(): Argument #1 ($image) must be of type GdImage, bool given in ....

And here’s the code responsible for the error:
plugins/ewww-image-optimizer/common.php 9238

$image = imagecreatefrompng( $filename );
if ( imagecolortransparent( $image ) >= 0 ) {
   ewwwio_debug_message( 'transparency found' );
   return true;
}
ewwwio_debug_message( 'preparing to scan image' );

The issue comes when $image variable has a bool for the return value. There needs to be a check in case that happens. For now i’ve just added the check myself but it will get updated everytime the plugin updates and i need to redo it every time.

Here’s my solution

$image = imagecreatefrompng( $filename );
if(is_a($image, 'GDImage')){
  if ( imagecolortransparent( $image ) >= 0 ) {
    ewwwio_debug_message( 'transparency found' );
    return true;
  }
  ewwwio_debug_message( 'preparing to scan image' );
  for ( $y = 0; $y < $height; $y++ ) {
    for ( $x = 0; $x < $width; $x++ ) {
      $color = imagecolorat( $image, $x, $y );
      $rgb   = imagecolorsforindex( $image, $color );
      if ( $rgb['alpha'] > 0 ) {
	ewwwio_debug_message( 'transparency found' );
	return true;
      }
    }
  }
}

• This topic was modified 3 years ago by elyrko.
• This topic was modified 3 years ago by elyrko.